Electrical power distribution systems often include overhead electrical power distribution lines mounted upon poles by a wide variety of mounting structure. Other distribution systems include underground distribution lines in which protected cables run under the ground surface. It is often necessary to take phase-to-phase voltage measurements across transmission lines while testing for induced or live power lines or equipment.
Known high voltage safety line detectors, meters and testers comprise high resistance probes connected in series with a calibrated panel meter to read the voltage across the phase-to-phase or phase-to-ground terminals. They are designed for use as safety tools by high voltage line maintenance workers to verify the status of the line or equipment as nominal, induced or de-energized. Known devices for providing such measurements include contact type and non-contact type. With contact type a reference probe or transmitter and a meter probe or receiver are connected in series with a cable as the loop is closed with load terminals.
Phasing and phase angle measurement on utility grid lines are critical for rapid load balancing, identifying faulty circuits, and maintenance of the grid lines. Even though feeder circuits are designed to be well balanced in the initial deployment, one of the phases may turn out to be more heavily loaded than others, leading to load imbalance conditions. Phasing meters facilitate the rebalancing of the phases and provide for rapid maintenance and restoration of clean grid systems in the field.
The probes need to be attached to hot sticks for reaching the overhead lines and to meet the safety requirements. The line workers hold the sticks and hook the meter to power lines for detection/measurement, as shown in FIG. 1. At times the workers are in difficult environments where inadequate lighting and the distance from the meter make it very difficult for reading the phasing meter. This can make it more difficult to read the status of the line voltage, phase angle and other parameters without looking at the meter. Even with the non-contact type meters the probes need to be read before and during maintenance.
To assist in various environments displays could be analog, digital or provide status indication using LED's. Known meters come with back light for increasing visibility. Digital displays make it easier to read the meter with minimal lighting. Color coded LEDs are used for status indication of the electrical lines. Buzzers may indicate over voltage status by generating beep sounds. Nevertheless, reaching nearby lines and reading at hazardous and hard environment remain an issue.
The present disclosure is directed to improvements in high voltage phasing meters.